Glial fibrillary acidic protein (GFAP) is a protein that is mainly expressed in astrocytes, a type of glial cell found in the central nervous system (CNS). GFAP is a cytoskeletal protein, meaning that it plays a role in maintaining the structure and shape of cells.

In astrocytes, GFAP is involved in providing structural support to the nervous system, as well as in regulating the extracellular environment of the brain. It is also involved in processes such as cell migration and proliferation.

GFAP is often used as a marker for astrocytes in both research and diagnostic settings. By staining for GFAP in brain tissue, researchers and clinicians can identify astrocytes and study their distribution, morphology, and function in the CNS. In addition, abnormal levels of GFAP in the cerebrospinal fluid (CSF) have been associated with various neurological disorders, such as brain injury, multiple sclerosis, and certain types of brain tumors.

Overall, GFAP is an important protein in astrocytes that plays a role in both the structure and function of the CNS, and is a valuable tool for studying and diagnosing neurological disorders.